PROJECT SUMMARY/ABSTRACT: The major goal of this application is to sustain the Specific Pathogen Free (SPF) program at the Caribbean Primate Research Center's (CPRC) through support of operations, administration, veterinary care, virological and MHC typing and by the improvement of our comprehensive genetic management plan. A unique feature of CPRC animals in favoring a successful establishment and sustainable of SPF colony are that these animals are naturally free of SIV and SRV-D, two of the four viruses to be tested for. Nevertheless, for safety and as required for the SPF Program, we continue systematically testing for all four viruses (B virus, STLV, SIV and SRV-D). The Program provides unadmixed Indian-origin rhesus monkeys with defined genetic and virological background. The population genetic analyses revealed that the SPF colony has remained genetically homogenous over time with sufficient amounts of heterozygosity and minimal stratification from its non-SPF founders. Genetic variation will be maintained in the SPF colony using the genetic management strategies described in this application. The genetic management approach will allow for enrichment of desired MHC markers in demand for biomedical research while maintaining genetic diversity. This specific core is designed to continue our current efforts to maintain a genetically diverse, MHC-defined SPF Indian-origin rhesus macaque colony for use in AIDS-related research. In 2015, the KDL began its collaboration with the current U42 to design and improve the SPF breeding colony to enhance the efficiency of colony maintenance as well as to maximize genetic heterogeneity of the colony animals. Since then we have been constructing multigenerational SPF pedigrees at the CPRC which can be traced back to founders in the Cayo Santiago island population.